I know black widow spiders are beneficial and seldom bite, but if you have kids around your garden, teach them to identify them. They seem to like to hide under cardboard mulch. Saw one today when I lifted a piece, and it reminded me of the year when I mulched the whole garden (different location) with cardboard and hundreds or maybe thousands hatched under there. They didn't bite, but I started really watching my hands, instead of just grabbing tomatoes by feel. Another year I did get a severely serious mysterious bite or sting from something in the garden. Could have been one, I guess.